In general, a fluoride such as BF3 or NF3, a chloride such as BCl3 or SnCl4, a bromide such as HBr, or the like is used as a treating gas for various treatments in the manufacturing process of semiconductors, liquid crystal devices and the like, so that there is a problem that parts in the treating vessel are considerably corroded and damaged.
For instance, as a material used in the plasma-treating vessel for the semiconductor manufacturing apparatus, there are known a metallic material such as Al, Al alloy or the like, an anodized oxide film of Al covering the surface of the metallic material, a sprayed coating such as boron carbide or the like, a sintered body film of Al2O3, Si3N4 or the like, and a high polymer film of fluorine resin, epoxy resin or the like. These materials are known to be subjected to a chemical damage when being contacted with a halogen ion indicating a strong corrosive property, or to an erosion damage through fines particles of SiO2 and Si3N4 and an ion excited by a plasma.
Especially, a plasma is frequently used for more activating the reaction in the process using a halogen compound. However, the halogen compound is dissociated to atomic F, Cl, Br, I or the like indicating a very strong corrosive property under an environment using such a plasma. Even in this case, if a finely divided solid of SiO2, Si3N4, Si, W or the like is existent in such an environment, the member used in the plasma-treating vessel is strongly subjected to not only the chemical corrosion but also the erosion damage through the above fine particles.
And also, the environment excited by the plasma is ionized even by a gas having no corrosive property such as Ar gas to cause a phenomenon of strongly impinging to a solid face (ion bombardment), so that various members arranged in the above vessel are subjected to a stronger damage.
Heretofore, there was a method of forming a then Al2O3 film or the like as a technique adopted when being subjected to such a chemical corrosion or erosion damage. However, such a technique has the following problems.
(1) With respect to a material covered with Al2O3 film (alumite) by subjecting Al and Al alloy to an anodization to provide corrosion resistance, there is a problem that the service life becomes shorter when being subjected to plasma erosion in an environment containing a halogen gas. And also, since it is an Al-containing film, AlF3 particles are created, which bring about a fear of degrading quality of semiconductor product manufactured.
(2) There is a technique that a dense film of oxide, carbide, nitride, fluoride or the like of Group 3a element in the Periodic Table such as Sc, Y, La, Ce, Yb, Eu, Dy or the like is formed on the surface of a part through PVD or CVD process, or a single crystal of Y2O3 is applied thereto (JP-A-10-4083). However, this technique has problems that the film forming rate is slow and the productivity is poor and plural film members (composite film) can not simultaneously be formed.
It is, therefore, an object of the invention to propose a surface-treated member for plasma-treating vessel or the like having large resistances to damage due to chemical corrosion and damage through plasma erosion under environment containing a halogen gas as well as a method of producing the same.